Coaxial connecting part

ABSTRACT

The invention relates to a coaxial connecting part which is used to connect a coaxial plug socket to a circuit carrier in an internal conductor. An elastically flexible bellows made of a conductive material is incorporated therein in order to keep axial and radial forces, occurring at the beginning of the socket, away from the substrate.

The invention relates to a coaxial connecting element for connecting acoaxial jack to a circuit carrier.

In measuring devices used in high-frequency technology, the coaxial jackused as the measurement port, which is installed in the front panel ofthe measuring device and is accessible from the outside, is generallyconnected via a portion of coaxial line to the printed conductor of theactual measuring-device circuit formed on a planar circuit carrier(substrate), and the inner conductor of this portion of coaxial line isattached to the printed conductor of the circuit carrier, for example,by soldering. Forces acting on the outer conductor of the coaxial jackare absorbed in the housing, because the coaxial jack and the housingare connected to one another via a screw connection. By contrast, theconnection between the inner conductor and the printed conductor of thesubstrate is mechanically very sensitive. Even extremely small axial orradial forces in the inner conductor can damage the circuit carrierand/or its printed conductors. Such axial and/or radial forces aregenerated primarily by the user when screwing and unscrewing the plug ofthe measurement cable to and from the coaxial jack of the measuringdevice, because even with very careful processing of the jacks, theinner conductor is moved in an axial and radial manner when screwing andunscrewing the plug, and these small movements of the inner conductorare then sufficient to damage the circuit carrier as mentioned above.

The object of the invention is therefore to provide a coaxial connectingelement, which prevents such damage to the circuit carrier by the innerconductor.

This object is solved on the basis of a coaxial connecting elementaccording to the preamble of the independent claim by its characterisingfeatures. Advantageous further developments are specified in thedependent claims.

As a result of the bellows interconnected in the inner conductor, anyaxial and/or radial forces occurring in the inner conductor are absorbedand therefore kept away from the sensitive connecting position betweenthe inner conductor and the printed conductor of the planar circuitcarrier. The connecting element according to the invention, which ispreferably integrated directly in the coaxial jack with the bellowsincorporated in the inner conductor, is therefore particularly suitablefor high-frequency electronic measuring devices, wherein measuringcables are frequently screwed and unscrewed to and from theexternally-accessible coaxial measurement ports, generally mounted onthe front panel, and wherein the inner conductor is therefore exposed tostrong axial and radial forces especially in cases of rough handling. Inspite of the bellows, the connecting element according to the inventioncan be manufactured with extremely low reflection.

The inner conductor according to the invention, which is resilient inthe axial and radial directions, is in fact particularly advantageous inmeasuring devices with coaxial jacks accessible from the outside, butcan also be used successfully with all coaxial systems such as jacks,plugs, probe tips or similar, of which the inner conductors are exposedduring operation to axial and radial forces, and which are connected atthe other end to a sensitive substrate circuit.

The invention is explained in greater detail below on the basis of anexemplary implementation with reference to schematic drawings. Thedrawings are as follows:

FIG. 1 shows in a partial perspective view the connection between acoaxial jack of a measuring device with a circuit carrier (substrate)installed in the interior of the measuring device; and

FIG. 2 shows details of the coaxial connecting element used in thiscontext in an enlarged view.

A coaxial jack 2, which is used as a measurement port and of which theinner conductor 3 is connected in the interior of the housing to thecircuit of the measuring device formed on a planar circuit carrier 4, ismounted in the front panel 1 of a high-frequency measuring device, whichis illustrated in FIG. 1 only in a fragmentary manner. The end 5 of theinner conductor inside the device is connected to the printed conductorsof the circuit carrier 4, for example, by soldering. The inner conductor3 of the jack 2 is held in the outer-conductor sleeves 6, 8 via asupport disk 7 made of an isolating material.

Another outer-conductor sleeve 8, which accommodates an inner conductor9, which connects the inner conductor 3 of the jack to the connectingend 5 on the circuit carrier 4, is inserted in the outer-conductorsleeve 6 of the jack 2.

The details of this coaxial connecting element are shown in an enlargedscale in FIG. 2. The inner conductor 9 is held in a concentric mannerbetween the two supports 7 and 10 integrated in the outer-conductorsleeve and screwed with the inner conductors 3, 5 into the correspondingsupports 7, 10. It is divided in the middle, and a resilient bellows 11is inserted between its two halves 14 and 15. The inner-conductor halves14 and 15 each provide end-face boreholes 12, into which pin-likeprojections 13 projecting axially from the bellows 11 are inserted. Thebellows 11 is held between the inner conductor halves 14 and 15 in thismanner.

The bellows 11, which is hollow inside, preferably consists of a thinfoil-like nickel material, which is gold plated on the outside. In orderto manufacture this resilient, thin-walled bellows, a blank of aluminiumis first manufactured with the required contour, to the outside of whicha thin nickel coating is then applied in a galvanic manner. This isfinally gold plated.

The inner aluminium blank is then etched away to provide an extremelythin-walled bellows with a corrugated outer coating made of gold-platednickel. The axially-projecting pin-like holding portions 13 of thebellows 11 are also manufactured in the same manner as hollow pins.

The contour of the bellows 11 is preferably selected in such a mannerthat the specified standard characteristic impedance of, for example, 50ohms is provided even at the position of the bellows within the coaxialouter-conductor sleeve 8. This can be calculated and implemented using a3-D simulator for high-frequency electromagnetic problems.

The resilient bellows can be deformed in a resilient manner in the axialdirection as well as to a limited extent in the radial direction, and inthis manner, forces, which act on the inner conductor 3 during thescrewing and unscrewing of the measurement cable to and from the jack 2by the user, can be absorbed. The bellows prevents such forces frombeing transferred from the inner conductor 3 of the jack to theinner-conductor end 5 at the connecting position with the substrate 4.

The invention is not restricted to the exemplary implementationpresented. The elements described can be combined with one another asrequired.

1. A connector for connecting a coaxial jack to a circuit carrier,comprising: an outer conductive sleeve; a conductive bellows havingaxial pins extending outwardly therefrom; a first inner conductorpositioned within the outer conductive sleeve having a first end and asecond end, wherein the first end is supported by an insulator and isconnectable to an inner conductor of the coaxial jack; and a secondinner conductor positioned within the outer conductive sleeve having afirst end and a second end, wherein the first end is supported by aninsulator and is connectable to the circuit carrier; wherein the secondends of the first and second inner conductors are separated by a gapwithin the outer conductive sleeve and have opposing axial bores intowhich the axial pins of the conductive bellows are fitted.
 2. Theconnector of claim 1, wherein the conductive bellows has a contourselected to maintain a characteristic impedance of the connector at thebellows.
 3. The connector of claim 1, wherein the conductive bellows ismade of a thin-walled, gold-plated nickel material.
 4. The connector ofclaim 1, wherein the insulators on the first and second inner conductorsmaintain a radial spacing between the first ends of the first and secondinner conductors and the outer conductive sleeve and are spaced from thesecond ends of the first and second inner conductors such that thesecond ends of the first and second inner conductors are unsupported inthe outer conductive sleeve.